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function [featureVector, ValidPoints]=extractFeatures(image,points,class,varargin)
// This function is used to extract interest point descriptors
//
// Calling Sequence
// [features, validPoints] = extractFeatures(Image, points, Class, Name, Value... )
//
// Parameters
// Image: Input Image, should be a 2-D grayscale. The Input Image should be real
// points: M-by-2 vector containing the list of Interest Points
// Class: The Name of the feature detecting algorithm used for interest point detection
// Method: The desired algorithm to be used for feature vector calculation
// Metric: M-by-1 vector containing the strength of eack interest Point
// BlockSize: An odd integer scalar for defining a square neighbourhood centered at each interest point for Block Detection Method
// Upright: Rotation Invariance Flag specified as a boolean 'True' or 'False'. Default Value: False(0)
// SURFSize: Length of SURF Feature Vector. Values: [64(default)|128]
// Orientation: M-by-1 vector containing the orientation of the detected feature in radians
// Axes: M-by-2 vector containing the axes length values detected for MSER Object
// Scale: M-by-1 vector containing the scale of detection of each Interest Point
// SignOfLaplacian: M-by-1 vector containing the values of Sign of Laplacian of a SURF Object
// features: M-by-N Feature Matrix containing M feature vectors each of length N
// validPoints: M-by-2 Matrix containing the set of valid points whose features have been extracted
//
// Description
// The function derives the descriptors from pixels surrounding an interest point, where each interest point specifies the location of the detected region center.
//
// Examples
// image = imread('sample.jpg');
// [corners count metric] = detectHarrisFeatures(image);
// [features, valid_corners] = extractFeatures(image, corners, "Class", "cornerPoints", "Metric", metric);
//
// Authors
// Umang Agrawal
// Sridhar Reddy
[lhs rhs]=argn(0);
if lhs>2
error(msprintf(" Too many output arguments"));
elseif rhs>13
error(msprintf(" Too many input arguments"));
end
imageList=mattolist(image);
//default values
blockSize=0;
upright=1;
surfSize=64;
if (class=="cornerPoints" | class=="BRISKPoints")
method="FREAK";
elseif (class=="MSERRegions" | class=="SURFPoints")
method="SURF";
elseif (class=="Matrix")
method="Block";
else
error(msprintf(" Invalid class type, check documentation for the list of valid types"));
end
//Count to ensure argument called only once
count_metric=0,count_orientation,count_scale,count_axes,count_signOfLaplacian;
count_method=0, count_block=0, count_surf=0, count_upright=0;
//Parsing input arguments
for i=1:rhs-3
if (varargin(i)=="Metric")
if(count_metric==0)
i=i+1;
metric=varargin(i);
else
error(msprintf(" Metric argument has been called twice"));
end
elseif (varargin(i)=="Orientation")
if(count_orientation==0)
i=i+1;
orientation=varargin(i);
else
error(msprintf(" Orientation argument has been called twice"));
end
elseif (varargin(i)=="Scale")
if(count_scale==0)
i=i+1;
scale=varargin(i);
else
error(msprintf(" Scale argument has been called twice"));
end
elseif (varargin(i)=="Axes")
if(count_axes==0)
i=i+1;
axes=varargin(i);
else
error(msprintf(" Axes argument has been called twice"));
end
elseif (varargin(i)=="SignOfLaplacian")
if(count_signOfLaplacian==0)
i=i+1;
signOfLaplacian=varargin(i);
else
error(msprintf("SignOfLaplacian argument has been called twice"));
end
elseif (varargin(i)=="Method")
if(count_method==0)
i=i+1;
method=varargin(i);
else
error(msprintf("Method argument has been called twice"));
end
elseif (varargin(i)=="BlockSize")
if(count_block==0)
i=i+1;
blockSize=varargin(i);
else
error(msprintf("BlockSize argument has been called twice"));
end
elseif (varargin(i)=="SurfSize")
if(count_surf==0)
i=i+1;
surfSize=varargin(i);
else
error(msprintf("SurfSize argument has been called twice"));
end
elseif (varargin(i)=="Upright")
if(count_upright==0)
i=i+1;
upright=varargin(i);
else
error(msprintf("Upright argument has been called twice"));
end
else
error(msprintf("Wrong argument, check documentation for the list of valid arguments"));
end
end
select class
case "cornerPoints" then
if(count_metric==0)
error(msprintf("For cornerPoints Class Metric argument is necessary"));
end
[featureVectors ValidPoints numBits numFeatures count metric]=extractFeatures(imageList, points, "Class", class, "Method", method, "surfSize", surfSize, "blockSize", blockSize, "upright", upright, "Metric",metric);
case "BRISKPoints" then
if(count_metric==0 | count_scale==0 | count_orientation==0)
error(msprintf("For BRISKPoints Class Metric, Orientation and Scale arguments are necessary"));
end
[featureVectors ValidPoints numBits numFeatures scale metrix orientation count]=extractFeatures(imageList, points, "Class", class, "Method", method, "surfSize", surfSize, "blockSize", blockSize, "upright", upright, "Metric",metric,"Orientation",orientation,"Scale",scale);
case "MSERRegions" then
if( count_orientation==0 | count_axes==0)
error(msprintf("For MSERRegions Class Orientation Matrix and Axes Matrix arguments are necessary."));
end
[featureVectors ValidPoints numBits numFeatures count axes orientation]=extractFeatures(imageList, points, "Class", class, "Method", method, "surfSize", surfSize, "blockSize", blockSize, "upright", upright, "Metric",metric,"Orientation",orientation,"Axes",axes);
case "SURFPoints" then
if(count_scale==0 | count_metric==0 | count_signOfLaplacian==0 | count_orientation==0)
error(msprintf("For SURFPoints Class Metric, Orientation, Scale and SignOfLaplacian arguments are necessary"));
end
[featureVectors ValidPoints numBits numFeatures count scale metrix signOfLaplacian orientation]=extractFeatures(imageList, points, "Class", class, "Method", method, "surfSize", surfSize, "blockSize", blockSize, "upright", upright, "Metric",metric,"Orientation",orientation,"Scale",scale,"SignOfLaplacian",signOfLaplacian);
case "Matrix" then
if(count_block==0)
error(msprintf("For Matrix Class BlockSize argument is necessary"));
end
[featureVectors ValidPoints numBits numFeatures]=extractFeatures(imageList, points, "Class", class, "Method", method, "surfSize", surfSize, "blockSize", blockSize, "upright", upright,"BlockSize",blockSize);
end
featureVector=struct("Type","binaryFeatures",'Features',featureVectors,'NumBits',numBits,'NumFeatures',numFeatures);
endfunction
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